GE MM300 manual Electrical Interface, Data Frame Format and Data Rate, Data Packet Format

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RS485 INTERFACE (MODBUS RTU)

COMMUNICATIONS GUIDE

RS485 interface (Modbus RTU)

The RS485 interface is a serial two-wire port intended for use as a Modbus RTU slave. The

RS485 port has the following characteristics.

•Address: 1 to 254

•Baud rate: 9600 to 115200 bps

•Supported Modbus function codes: 3, 4, 5, 6, 7, 8, 16

Modbus Protocol

The MM300 implements a subset of the Modicon Modbus RTU serial communication standard. The Modbus protocol is hardware-independent. That is, the physical layer can be any of a variety of standard hardware configurations. This includes RS232, RS422, RS485, fibre optics, etc. Modbus is a single master / multiple slave type of protocol suitable for a multi-drop configuration as provided by RS485 hardware. The MM300 Modbus implementation employs two-wire RS485 hardware. Using RS485, up to 32 MM300s can be daisy-chained together on a single communication channel.

The MM300 is always a Modbus slave. It can not be programmed as a Modbus master. Computers or PLCs are commonly programmed as masters.

Both monitoring and control are possible using read and write register commands. Other commands are supported to provide additional functions.

Electrical Interface

The hardware or electrical interface in the MM300 is two-wire RS485. In a two-wire link, data is transmitted and received over the same two wires. Although RS485 two wire communication is bi-directional, the data is never transmitted and received at the same time. This means that the data flow is half duplex.

RS485 lines should be connected in a daisy chain configuration with terminating networks installed at each end of the link (i.e. at the master end and at the slave farthest from the master). The terminating network should consist of a 120 W resistor in series with a 1 nF ceramic capacitor when used with Belden 9841 RS485 wire. Shielded wire should always be used to minimize noise. The shield should be connected to all of the MM300s as well as the master, then grounded at one location only. This keeps the ground potential at the same level for all of the devices on the serial link.

Polarity is important in RS485 communications. The '+' (positive) terminals of every device must be connected together.

NOTE

Data Frame Format and Data Rate

One data frame of an asynchronous transmission to or from a MM300 typically consists of 1 start bit, 8 data bits, and 1 stop bit. This produces a 10 bit data frame. This is important for transmission through modems at high bit rates (11 bit data frames are not supported by Hayes modems at bit rates of greater than 300 bps).

Modbus protocol can be implemented at any standard communication speed. The MM300supports operation at 9600, 19200, 38400, 57600, and 115200 baud.

Data Packet Format

A complete request/response sequence consists of the following bytes (transmitted as separate data frames):

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MM300 MOTOR MANAGEMENT SYSTEM – COMMUNICATIONS GUIDE

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Contents MM300 Page Table of Contents MM300 Motor Management System Communications Guide MM300 Motor Management System Communications Guide Electrical Interface Data Frame Format and Data RateData Packet Format Error Checking CRC-16 AlgorithmTiming MM300 supported functionsFunction Code 03H Master Transmission Bytes Example Description Function Code 04HMaster/slave packet format for function code 03H Slave Response Bytes Example DescriptionFunction Code 05H Master/slave packet format for function code 04HMaster/slave packet format for function code 05H Data Function Code 06HMaster/slave packet format for function code 06H CRC CB B9Function Code 07H Function code 7 bitmaskMaster/slave packet format for function code 07H Master/slave packet format for function code 08H Function Code 08HFunction Code 10H Diag CodeError Responses Master/slave packet format for function code 10HModbus memory map Actual ValuesGeneral Timers REAL-TIME ClockTrip Counters Status Motor CONTACT/VIRTUAL INPUTS/OUTPUTS StatusSecurity Current MeteringPower Metering GCP Factory Test FLA RTD Maximium TemperatureMotor Starting Learned Data User MAP ValuesEvent Recorder Status BufferFlexlogic Setpoints CommandsCommunication Settings CommunicationREAL-TIME CLOCK/DAYLIGHT Savings Current SensingMotor Data Setup Voltage SensingProcess Interlock RS485 Interface Modbus RTU Communication Setup Open Control CircuitUser MAP Addresses Reset Setup Mechanical JAMRTD OPEN/SHORT Circuit REQUIRED=IOG Thermistor CPUUndercurrent REQUIRED=IOA Underpower IOA + IOC or IOA + IOBGround Fault FLAPhase Reversal REQUIRED=IOB Phase Undervoltage REQUIRED=IOBPhase Overvoltage REQUIRED=IOB Load IncreaseStart Inhibit MaintenanceFlexlogic Timers Restart BlockCommunications Guide RS485 Interface Modbus RTU Communications Guide RS485 Interface Modbus RTU Contact Input Assignment Contact Outputs Auto / Manual ControlFlexlogic Equation Unsigned VALUE, 2 Decimal Places Unsigned ValueUnsigned VALUE, 1 Decimal Place Unsigned Long ValueMSB Unsigned Long VALUE, 3 Decimal PlacesDate MM/DD/YYYY LSBOFF / no On / YESOFF USER1 USER2USER3 No Event/Trip To Date RS485 Interface Modbus RTU RS485 Interface Modbus RTU Not XOR Latch NOR Nand Timer Assign RS485 Interface Modbus RTU Definition RS485 Interface Modbus RTU TUE SUNMON WEDVbn Direct Bit FC180 FC181 FC182 FC183 RS485 Interface Modbus RTU Performing Commands Using Function Code 10H Using the User Definable Memory Map Master/slave packet format for performing commandsCRC 7E CE RS485 Interface Modbus RTU Ethernet interface Profibus LED indications Profibus Output DataFieldbus interface external connections Profibus LEDProfibus Input Data Profibus DP-DiagnosticsSystem Standard Diagnostics Bytes 1 through F1BCommunications Guide Fieldbus Interface DeviceNet LED indications DeviceNet CommunicationsFieldbus interface external connections DeviceNet Class ObjectIdentity Object Class Code 01H Message Router Class Code 02HDeviceNet Object Class Code 03H DeviceNet Connection Object Class Code 05H Connection Object, Class Code 05h, ServicesAttribute Access Name Data Type Value Description Identity Object, Class Code 03h, Instance 01h, AttributesMotor Data Object, Class Code A0h, Services DeviceNet Motor Data Poll, Explicit Object Class Code A0HMotor Data Object, Class Code A0h, Attributes Item Description Size in Bytes Format Explicit Motor Analog Data Object, Class Code B0h, Services Attribute Description Size in Bytes0FH Data Formats, Explicit Motor Analog Data Object Attribute Item Description Size Format BytesFieldbus Interface Explicit Motor Control Object, Class Code B1h, Attributes Explicit Motor Control Object, Class Code B1h, ServicesDeviceNet Explicit Motor Object, Class Code B1H Data Value, Class B1hFieldbus Interface

MM300 specifications

The GE MM300 is a robust and versatile controller designed primarily for industrial automation applications. Built to tackle the demands of modern manufacturing environments, this controller offers a range of features that contribute to its popularity among engineers and operators.

One of the standout features of the GE MM300 is its scalability. The device can be easily configured to meet the needs of both small and large systems. Its modular architecture allows users to add or remove components based on the specific requirements of their applications, facilitating a more tailored approach to automation.

The MM300 supports various communication protocols, including Ethernet/IP, Modbus TCP, and more, ensuring seamless integration with a variety of devices and systems. This feature significantly enhances interoperability, allowing users to connect the controller to existing infrastructure without extensive reconfiguration.

In terms of processing power, the MM300 is equipped with a high-performance processor that can handle complex tasks with ease. With advanced data handling capabilities, it supports real-time data processing, enabling faster decision-making and improving overall operational efficiency. This capability is particularly beneficial for applications requiring precise control and monitoring.

Moreover, the GE MM300 boasts a user-friendly interface, featuring an intuitive programming environment that simplifies the development of control applications. This includes an integrated development environment (IDE) and support for popular programming languages, making it accessible for both seasoned programmers and those new to automation technologies.

The device is designed to operate in challenging industrial conditions, featuring a rugged construction that ensures durability and longevity. Its ability to withstand extreme temperatures, vibrations, and other environmental stressors enhances its reliability in demanding applications, which is crucial for minimizing downtime in production processes.

Security is another critical aspect of the GE MM300. The controller incorporates advanced security features to protect against unauthorized access and cyber threats, helping organizations ensure the integrity of their operations.

In summary, the GE MM300 stands out due to its scalability, versatile communication options, high processing capabilities, user-friendly programming environment, rugged design, and security features. These characteristics make it a reliable choice for industries seeking to enhance their automation processes and improve overall efficiency. Whether for small-scale or large-scale applications, the MM300 provides a comprehensive solution to meet the evolving needs of modern manufacturing.
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